MAPPING OF A LOCUS CONTROLLING RESISTANCE TO ALBUGO-CANDIDA IN BRASSICA-NAPUS USING MOLECULAR MARKERS

White rust, caused by Albugo candida, is an important disease of cruci fers, vegetables, and oilseeds in many countries. A backcross populati on, BCP2, as well as F-1-derived doubled-haploid (DH) and F-2 populati ons obtained from the same single F-1 plant, produced from the cultiva r Major X Stellar, were used to study the genetic control of resistanc e to white rust in Brassica napus. The control of resistance to white rust in this cross was attributed to a dominant allele at a single loc us, designated ACA1. Other loci may be involved in the control of the intensity of sporulation of the fungus in the plant. The ACA1 locus wa s mapped with respect to restriction fragment length polymorphism (RFL P) loci in the F1DH population. Linkage between the ACA1 locus and nin e RFLP loci was observed on linkage group 9 of a B. napus RFLP linkage map.